1. Field of the Invention
The invention relates to an optical disc having a spoiler and the method for fabricating the same.
2. Description of Related Art
The optical disc industry has been working on optical discs having higher rotational speed in keeping up with the demand for higher data transmission rates. Vibration or wobbling of the optical disc can occur when the disc undergoes rotation at a high speed. Such vibration can be due to rotation of the disc drive shaft or air resistance associated with the motion of the disc, both of which are major factors for causing the vibration. In the past the vibration of the optical disc was briefly looked at in the industry, and several solutions to this problem were offered but it did not generate much interest because the air resistance due to the then lower rotational speed was not too great an issue.
Today, it is not uncommon to see an optical disc rotate at a speed over 10,000 rpm. At such a high rotational speed, the air resistance so caused has caught more attention. An increase in air resistance caused by increasing the rotational speed of the optical disc not only causes the disc to vibrate but also increases the power consumption by the rotation motor driving the shaft. The latter phenomenon causes the optical read/write accuracy to vary, which affects the read/write characteristics and further weakens the drive's internal chip operation; deformation of the optical disc can also occur due to operation under high temperature, thus resulting in problems while reading/writing the optical disc or even inability to read due to disc damage. Moreover, the optical disc could deform under the high temperature, causing the read/write quality to deteriorate. In the worst scenario, the air resistance can inflict physical damages to the optical disc or even cause the optical disc to disintegrate.
There are known techniques for decreasing the vibration of a rotating optical disc by reducing the air resistance encountered by the disc. Most of the conventional techniques have considered changing the disc drive's structure to improve the airflow. For example, U.S. Pat. No. 7,181,749 discloses means for an optical disc to rotate with stability by adjusting the distance between the disc drive's upper cover and the disc such that there is a lowered pressure difference between the upper and the lower surfaces of the disc; and US Patent Application Publication No. 2006-0048171 discloses an improved shape of the upper cover of an optical disc drive having a function of guiding the airflow smoothly to stabilize the disc. These conventional techniques, however, may not be more effective or cost-effective than directly implementing airflow-altering structures on the optical disc per se.